The launch of Google Inc.’s Android KitKat, the next version of the most widely used operating software for smartphones and tablets, is drawing near. Google executives haven’t announced a release date but people who have been briefed on KitKat say that it is coming soon.

There have been several reports about KitKat’s likely features based on leaked screenshots and leaked photos of the Nexus 5 smartphone that will be the first device to show off those features. But we’ve reviewed a confidential file that Google shared with companies that make Android devices to explain the most important new features. (A Google spokeswoman didn’t respond to requests for comment.) Here’s what we know.

One Android to rule them all?

With KitKat, Google has worked even harder to address one of Android’s biggest disadvantages versus Apple: less than half of Android devices are running the latest version of the software, called “Jelly Bean,” which was released in summer 2012. Nearly two-thirds of Apple devices already are running the latest version of its iOS software, released last month, the company has said.

This Android fragmentation makes it tougher for Android app developers to run the latest versions of their services across all Android devices. Some earlier releases of Android were better suited to higher-end devices that have more memory capacity for all the newest features. As a result, cheaper phone makers sometimes ended up using older versions of Android.

The document about KitKat that we reviewed, marked “confidential,” makes clear that Google wants its new software to work well on low-end phones in addition to the more expensive Samsung Galaxy and HTC devices.

KitKat “optimizes memory use in every major component” and provides “tools to help developers create memory-efficient applications” for “entry-level devices,” such as those that have 512 megabytes of memory, according to the document.

Google has long sought ways to help make the newest versions of Android compatible with low-cost devices, the kind that are proliferating in developing countries with the help of manufacturers like Huawei, ZTE, and others. This time Google has been more proactive with makers of lower-memory devices, said people who have been briefed on that matter.

Questions remain about whether the effort will bear fruit. In many markets, wireless carriers don’t do a good job of pushing software upgrades to existing Android devices that already have been sold.

The improvements for low-memory devices also could help the software to better power wearable-computing devices.

Wearing it proudly

The KitKat release shows that Google is preparing for the rise of wearable-computing devices. According to the confidential document, KitKat is expected to support three new types of sensors: geomagnetic rotation vector, step detector and step counter.

These features are likely geared for forthcoming Android-powered smartwatch made by Google and possibly the company’s head-mounted Google Glass, as well as non-Google devices. Android smartphone apps that track people’s fitness also could get a boost from the new feature as more manufacturers pack motion sensors into devices.

There is another potential benefit to Android from supporting these kinds of sensors: Google will be able to tell how far someone walked based on the steps they took. That could come in handy as Google tries to map more indoor locations such as malls and airports, where GPS and WiFi sensors don’t always do a good enough job of pinpointing exactly where a smartphone user is located. It also could improve the walking directions that people use on Google Maps.

Another crack at NFC

KitKat will allow developers to create services to allow phones to “emulate” physical cards that let people make payments, earn loyalty rewards, enter secure buildings and public-transit system, according to the confidential document. But it’s unclear whether the change will spur growth in the area.

Google has been a huge proponent of Near-Field Communication technology, which allows phones to exchange data with other devices over distances of a few inches. The technology enables people to pay for things at stores with their phones, among other users. But the technology hasn’t gotten much adoption from app developers, nor has Apple embedded it in the iPhone.

On Android, adoption was slowed in part because developers couldn’t create apps that emulated what physical cards do in the real world without first getting permission from wireless carriers, says Einar Rosenberg, chief executive of Creating Revolutions, which makes NFC-based apps. That’s because carriers control a part of the phone called the “secure element” where a card owner’s personal information is stored.

According to the KitKat marketing materials, developers will be able to emulate cards without keeping people’s information stored in the secure element.

The biggest question mark about the feature is where the personal information will be stored without running the risk of getting manipulated or stolen by hackers, Mr. Rosenberg says.

Control the TV

Google wants your Android device to be a remote control. The next version of Android lets developers build apps that control TVs, tuners, switches and other devices by sending infrared signals.

Samsung and HTC devices already have built-in infrared “blasters” and both companies used a company called Peel to design an app that can control TVs. But KitKat will help developers avoid having to write different apps for different hardware makers because there will now be a standard way for all apps to tell the Android device to activate the blasters.

Bluetooth boost

Google wants Android apps to be able to interact with a wide variety of devices using Bluetooth technology. Those devices include joysticks, keyboards, and in-car entertainment systems. In KitKat, new support for something called Bluetooth HID over GATT and Bluetooth Message Access Profile will allow Android to talk to more devices than before.

We have oodles more details about Android KitKat but much of it is too technical to describe here. Find me on Twitter or Google+ if you have questions about features that will be included in the release.